// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/dns/single_request_host_resolver.h"

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/compiler_specific.h"
#include "base/logging.h"
#include "net/base/net_errors.h"

namespace net {

SingleRequestHostResolver::SingleRequestHostResolver(HostResolver* resolver)
    : resolver_(resolver)
    , cur_request_(NULL)
    , callback_(
          base::Bind(&SingleRequestHostResolver::OnResolveCompletion,
              base::Unretained(this)))
{
    DCHECK(resolver_ != NULL);
}

SingleRequestHostResolver::~SingleRequestHostResolver()
{
    Cancel();
}

int SingleRequestHostResolver::Resolve(const HostResolver::RequestInfo& info,
    RequestPriority priority,
    AddressList* addresses,
    const CompletionCallback& callback,
    const BoundNetLog& net_log)
{
    DCHECK(addresses);
    DCHECK_EQ(false, callback.is_null());
    DCHECK(cur_request_callback_.is_null()) << "resolver already in use";

    HostResolver::RequestHandle request = NULL;

    // We need to be notified of completion before |callback| is called, so that
    // we can clear out |cur_request_*|.
    CompletionCallback transient_callback = callback.is_null() ? CompletionCallback() : callback_;

    int rv = resolver_->Resolve(
        info, priority, addresses, transient_callback, &request, net_log);

    if (rv == ERR_IO_PENDING) {
        DCHECK_EQ(false, callback.is_null());
        // Cleared in OnResolveCompletion().
        cur_request_ = request;
        cur_request_callback_ = callback;
    }

    return rv;
}

void SingleRequestHostResolver::Cancel()
{
    if (!cur_request_callback_.is_null()) {
        resolver_->CancelRequest(cur_request_);
        cur_request_ = NULL;
        cur_request_callback_.Reset();
    }
}

void SingleRequestHostResolver::OnResolveCompletion(int result)
{
    DCHECK(cur_request_);
    DCHECK_EQ(false, cur_request_callback_.is_null());

    CompletionCallback callback = cur_request_callback_;

    // Clear the outstanding request information.
    cur_request_ = NULL;
    cur_request_callback_.Reset();

    // Call the user's original callback.
    callback.Run(result);
}

} // namespace net
